Field of the Invention
This invention is directed to a control system which is operative to establish a variable operative fuel mixture for powering a vehicle, comprising both gaseous fuel, such as natural gas, and distillate fuels, such as diesel, dependent at least in part, on predetermined ones of a plurality of operating modes and operating characteristics of the vehicle. The fuel control system is specifically adaptable for determining an efficient and effective operative fuel mixture for powering high capacity off-road vehicles such as mine haul trucks.
Description of the Related Art
Mine haul trucks are off-highway, two axle, rigid dump trucks, specifically engineered for use in high production mining and heavy duty construction environments. As such, haul truck capacities typically range from 50 short tons (45 tons) to 400 short tons (363 tons). In addition, the largest and highest payload capacity of such haul trucks are referred to as “ultra class” trucks. This ultra class includes haul trucks having a payload capacity of at least 300 short tons or greater. Numerous manufacturers throughout the world produce such mammoth vehicles which are engineered for both performance and long operable life. Trucks of this type are developed specifically for high production duty wherein material is transported in large quantities in order to lower transportation costs on a cost-per-ton basis.
Typically mine haul trucks are powered by either direct drive diesel or diesel electric power trains frequently including a multiple horse power turbo charged diesel engine. Due to the exceptional size and weight of such vehicles, they cannot be driven on public access roads, but are ideal for high production environments wherein massive quantities of material must be moved, handled, relocated, etc. on a continuous or regular basis.
Accordingly, it is well recognized that distillate fuels, specifically diesel, are used as the primary fuel source for such vehicles. Attempts to maximize the operational efficiency, while maintaining reasonable safety standards, have previously involved modified throttle control facilities. These attempts serve to diminish adverse effects of control mechanisms which may be potentially harmful to the vehicle engine operation as well as being uneconomical. Typical adverse effects include increased fuel consumption and wear on operative components. Therefore, many diesel engines and the vehicles powered thereby are expected to accommodate various types of high capacity payloads and provide maximum power for relatively significant periods of operation. As a result, many diesel engines associated with heavy duty and off-road vehicles are commonly operated at maximum or near maximum capacity resulting in an attempted maximum power delivery from the vehicle engine and consequent high rates of diesel consumption. It is generally recognized that the provision of a substantially rich fuel mixture in the cylinders of a diesel engine is necessary for providing maximum power when required. Such continued high capacity operation of the vehicle engine results not only in wear on the engine components but also in high fuel consumption rates, lower operating efficiencies, more frequent oil changes and higher costs of operation.
Accordingly, there is a long recognized need for a fuel control system specifically intended for use with high capacity, off-road vehicles including mine haul vehicles of the type generally described above that would allow the use of more efficient fueling methods using other commonly available fuel sources. Therefore, an improved fuel control system is proposed which is determinative of an effective and efficient operative fuel mixture comprised of a combination of gaseous and distillate fuels. More specifically, gaseous fuel can comprise natural gas or other appropriate gaseous type fuels, wherein distillate fuel would typically include diesel fuel.
Such a preferred and proposed fuel control system should be capable of regulating the composition of the operative fuel mixture on which the vehicle engine currently operates to include 100% distillate fuel, when the vehicle's operating mode(s) clearly indicate that the combination of gaseous and distillate fuels is not advantageous. Further, such a proposed fuel control system could have an included secondary function to act as a general safety system serving to monitor critical engine fuel system and chassis parameters. As a result, control facilities associated with such a preferred fuel control system should allow for discrete, user defined control and safety set points for various engine, fuel system and chassis parameters with pre-alarm, alarm and fault modes.